High performance fans are used in variety of industrial and laboratory applications such as, for example, heating, ventilating, and cooling systems. The performance and desirability of the fans are measured by the fan efficiency and acoustic level produced during operation. The improvement of fan efficiency will reduce the energy needed to operate the fan and/or increase output airflow and pressure.
Fan efficiency is affected by a number of factors. For example, the efficiency of a drive mechanism such as a motor and the revolving speed of the motor and blades may impact the fan energy efficiency. Another example of efficiency factors may include the clearance between the blades of a fan and an inner surface of the fan housing, as typically seen in axial-fans. The design of the fan housing also impacts the energy efficiency of the fan. Another important factor is the design of fan blades in term of shape and representing some structural advantages their orientation with respect to the rest of the fan.
Many of the efficiency factors discussed above are taken into account when issues of fan efficiency and acoustic noise are investigated. Primarily, the designer's attention is focused on improving the impeller design through unique airfoil blades or twisted flat blade designs. For example, centrifugal fans are categorized by their blades shapes into the following categories; 1) radial fans with flat blades, 2) forward curved fans with forward-curved blades, and 3) backward inclined fan with blades that tilt away from the direction of rotation.
Other structures such as, for example, three-dimensional blades with specific thickness distribution and hollow blades are also proposed. However, none of the above-mentioned structures provide a naturally fluid pathway, mating the blades' design and shape, for increasing air flow pressure and thereby reducing inefficiencies generated by flow separations along surfaces of the blades.
The present invention is proposed in view of the above aforementioned problems. The present invention provides a new design and orientation of impeller blades for improving the P-Q characteristics and energy efficiency of centrifugal fans.